The invention relates generally to illuminated messages, symbols or emblems for night visibility from the side of a vehicle cargo body or the like. The invention relates more specifically to the use of optical fiber technology to back-light a translucent panel carrying the message, symbols or emblems.
In the prior art, vehicle bodies have been painted with advertising and other messages. Obviously, such messages are not clearly visible at night. Such well-known arrangements as sign illumination using incandescent lamps, fluorescent lighting or even neon tube signs are known. However, all such prior art arrangements are expensive, fragile (especially the neon tubes) and require significant levels of maintenance.
Highway cargo vehicles of the semi-trailer or full trailer type are conventionally constructed as separate chassis units with container bodies mounted thereon and are pulled by tractor units.
The use of fiber-optic structures to convey light longitudinally and at the same time provide the needed lateral emission is known. U.S. Pat. No. 4,763,984 discloses an arrangement including a plurality of optic fibers extending in lateral juxtaposition in a plane to effect enhanced lateral light flux emission. However, that reference contains no disclosure of the unique structure of the invention.
In the usual fiber-optic system, longitudinal light signal conveyance is optimized and lateral transmission is minimized, the latter being regarded as undesired leakage. In such instances, the optical fiber core and cladding are constructed in accordance with well-known criteria to effect light flux propagation in lower order and fundamental modes.
The aforementioned U.S. Pat. No. 4,763,984 describes some principles, methods and structural variations in respect to optic fiber core size and other parameters for producing a desired ratio of longitudinal conveyance to lateral emission through a translucent cladding.
Other known prior art disclosing uses of lateral emissions from an end-energized light guide (optic fiber cable) includes U.S. Pat. Nos. 2,479,500 and 2,808,502.
Apparatus employing a specialized optic fiber light pipe is disclosed in U.S. Pat. No. 4,947,293. The applicant herein is the same as the patentee of that prior patent. The arrangement of U.S. Pat. No. 4,947,293 provides vehicle cargo body top perimeter lighting but shows no provision for illuminating any kind of message.